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5.6
Section 5
Fuel System and Governor
Troubleshooting Checklist
When the engine starts hard, runs roughly or stalls at
low idle speed, check the following areas before
adjusting or disassembling the carburetor.
• Make sure the fuel tank is filled with clean, fresh
gasoline.
• Make sure the fuel tank cap vent is not blocked
and that it is operating properly.
• Make sure fuel is reaching the carburetor. This
includes checking the fuel shut-off valve, fuel tank
filter screen, in-line fuel filter, fuel lines and fuel
pump for restrictions or faulty components as
necessary.
• Make sure the air cleaner base and carburetor
are securely fastened to the engine using gaskets
in good condition.
• Make sure the air cleaner element is clean and all
air cleaner components are fastened securely.
• Make sure the ignition system, governor system,
exhaust system, and throttle and choke controls
are operating properly.
If the engine is hard-starting or runs roughly, or stalls at
low idle speed, it may be necessary to service the
carburetor.
Troubleshooting – Carburetor Related Causes
Condition Possible Cause/Probable Remedy
1a. Low idle speed improperly adjusted. Adjust the low idle speed
screw.
b. Low idle fuel mixture circuit blocked/restricted. Clean carburetor as
required.
1. Engine starts hard, runs roughly or
stalls at idle speed.
2. Engine runs rich (indicated by
black, sooty exhaust smoke,
misfiring, loss of speed and power,
governor hunting, or excessive
throttle opening).
2a. Clogged air cleaner. Clean or replace.
b. Choke partially closed during operation. Check the choke lever/
linkage to ensure choke is operating properly.
c. Float level too high. Separate fuel bowl from carburetor body. Free
(if stuck), or replace float.
d. Dirt under the fuel inlet needle. Remove needle; clean needle and
seat and blow with compressed air.
e. Bowl vent or air bleeds plugged. Clean vent, ports, and air bleeds.
Blow out all passages with compressed air.
f. Leaky, cracked, or damaged float. Submerge float to check for
leaks.
3. Engine runs lean (indicated by
misfiring, loss of speed and power,
governor hunting, or excessive
throttle opening).
3a. Float level too low. Separate fuel bowl from carburetor body. Free
(if stuck), or replace float.
b. Idle holes plugged; dirt in fuel delivery channels. Clean main fuel
jet and all passages; blow out with compressed air.
4. Fuel leaks from carburetor.
4a. Float stuck. See Remedy 2d.
b. Dirt under fuel inlet needle. See Remedy 2e.
c. Bowl vents plugged. Blow out with compressed air.
d. Carburetor bowl gasket leaks. Replace gasket.